1. Field of the Invention
The present invention relates to disk rotation devices, and more specifically, to a disk rotation device rotationally driving a disk.
2. Description of the Related Art
Regarding recent improvements of digital technologies and technologies for data compression, an optical disk, such as a compact disk (CD) or digital versatile disk (DVD) having the same diameter as the CD where data approximately seven time as much as the data of the CD are recordable, is widely noticed as a medium for recording data such as music, a motion picture, a picture, an illustration and computer software. With the low cost of the optical disk, an optical disk driving apparatus, for which the optical disk is used as a medium for recording and reproducing data, comes into wide use as a peripheral device of personal computers.
Furthermore, recently, as the personal computer is being made miniaturized, light-weight, and thin, a notebook-type personal computer being capable of outside use is in the mainstream. An optical disk driving device installed in the notebook-type personal computer has a limitation of its thickness. Hence, a user himself/herself places the optical disk on a turn table connected to a spindle motor. Accordingly, the spindle motor is pulled out with a tray where the optical disk is mounted at a position where the optical disk is put on or taken off.
In the optical disk driving device, based on a request for discharging the optical disk, a control part electrically brakes the rotation of the spindle motor and a tray is pulled out in a state where the rotation of the optical disk is substantially stopped. Recently, the rotating speed of the optical disk has been made high, so that reproducing at a high speed such as 24 times speed (approximately 5000 rpm) is generally performed. It takes several seconds for such a high speed rotation to be electrically stopped. Hence, there is dissatisfaction of the user who likes to exchange the optical disk quickly.
In addition, the optical disk driving device has an emergency discharge mechanism for forcibly taking off the optical disk in a case where a normal discharging operation does not work due to a sudden power loss or malfunction. Electric braking is not performed by this emergency discharge mechanism. Hence, the optical disk is discharged while it is rotated at high speed and therefore it takes a time more than several tens of seconds to stop the rotation of the optical disk.
Because of this, various devices for reducing a time for stopping the rotation of the optical disk when the optical disk is discharged are suggested. See Japanese Patent No. 3258888 and Japanese Laid-Open Patent Publication No. 2000-76780, for example.
However, a disk reproduction device disclosed in Japanese Patent No. 3258888 has a disadvantage in that the device cannot correspond to optical disks having different diameters, such as a CD having a diameter of 12 cm and a CD having a diameter of 8 cm. Furthermore, in this disk reproduction device, only when the optical disk is situated in a designated area where the optical disk is being moved, an elastic body provided in a housing part comes in contact with the optical disk. Given that the rotational speed of the optical disk will be made higher in the future, it may not be possible to sufficiently reduce the rotational speed of the optical disk.
Furthermore, in the optical disk driving device installed in the notebook-type personal computer, generally, from the perspective of the prevention of degrading of an electrical signal and due to the thickness limitation, a circuit board where an interface with the personal computer is mounted is provided at a rear surface side, which is situated in a direction opposite to a disk discharge direction. Also, a head mechanism, including an optical pick up and an optical pick up sending mechanism, is situated at a discharging direction side (a disk mounting or dismounting position side) closer than the spindle motor. In this disk reproduction device disclosed in the Japanese Laid-Open Patent Publication No. 2000-76780, it is necessary to provide the elastic body coming in contact with the spindle motor at the disk mounting or dismounting position side closer than a position of the spindle motor at the time of reproduction and to avoid an interference between the head mechanism and the elastic body. Thus, the disk reproduction device disclosed in the Japanese Laid-Open Patent Publication No. 2000-76780 has a lot of limitation in design and therefore it is difficult to make the device thinner. Furthermore, in this disk reproduction device, only when the optical disk is situated in a designated area where the optical disk is being moved, an elastic body provided in a housing part comes in contact with the optical disk. Given that the rotational speed of the optical disk will be made higher in the future, it may not possible to sufficiently reduce the rotational speed of the optical disk.